(CNN) -- In a blistering speech before the United Nations General Assembly, Iranian President Mahmoud Ahmadinejad blamed "a few bullying powers" for creating the world's problems and said the "American empire in the world is reaching the end of its road."

And while he insisted Iran's nuclear activities are peaceful, Ahmadinejad blamed the same powers for seeking to hinder it "by exerting political and economic pressures on Iran, and threatening and pressuring" the International Atomic Energy Agency.

Those powers, meanwhile, are building or maintaining nuclear stockpiles themselves, unchecked by anyone, he said.

As Ahmadinejad spoke, the only person at the United States table was a note-taker; no U.S. diplomat was present. When President Bush spoke earlier Tuesday, however, Ahmadinejad was in the room.

CNN's Chief International Correspondent Christiane Amanpour said Ahmadinejad's comments were some of the most conciliatory he had made to the United States.

"As long as the aggressors, because of their financial, political and propaganda powers, not only escape punishment, but even claim righteousness, and as long as wars are started and nations are enslaved in order to win votes in elections, not only will the problems of the global community remain unsolved, but they will be increasingly exacerbated," the Iranian leader said.

He said Zionists in Israel "have forged a regime through collecting people from various parts of the world and bringing them to other people's land, by displacing, detaining and killing the true owners of that land."

The Security Council, he said, "cannot do anything, and sometimes under pressure from a few bullying powers, even paves the way for supporting these Zionist murders."

He stopped short of calling for Israel to be politically wiped off the map as he has in the past. He called for "a free referendum in Palestine for determining and establishing the type of state in the entire Palestinian lands."

Ahmadinejad pointed to what he said are signs of hope, saying an increasing number of nations are turning their backs on "the bullying powers" and seeking to establish new relations.

"Today the Zionist regime is on a definite slope to collapse," he said.

The Anti-Defamation League released a statement saying the Iranian leader showed he "is deeply infected with anti-Semitism" and displayed "the true threat the Iranian regime poses to Israel, the United States and the West."

Hours before Ahmadinejad's speech, Bush told the General Assembly that Iran was among the nations that "continue to sponsor terror."

"Yet their numbers are growing fewer, and they're growing more isolated from the world," Bush said.

Bush also said U.N. members needed to enforce sanctions against Iran for failing to suspend its nuclear program, which the United States and other Western nations believe is intended to develop nuclear weapons.

Before Ahmadinejad spoke to the U.N., he told CNN's Larry King that he is willing to meet with presidential candidates Sens. John McCain and Barack Obama -- even in front of the media -- to discuss world issues and debate.

"We believe that these are issues relating to the domestic affairs of the United States," Ahmadinejad told Larry King of the presidential race, according to a transcript of the interview.

"And decisions pertaining to that must be made by the American people. And it's not important to us either," Ahmadinejad said. "What matters essentially is that the president that is chosen by the American people should adopt a path and a policy approach and for us to observe the policy approach.

"This is the campaign period, anyone can say anything. So we disregard that. What matters is that once someone is in office, we have to watch and see if that person will bring about some changes in policy or continue the same old path."

Ahmadinejad was in New York City for the United Nations General Assembly meeting, which began Tuesday.

Asked whether he fears a U.S. attack, Ahmadinejad told King that attacking Iran would be the "worst thing the U.S. government can do ... I think that in the United States, there are enough reasonable people, smart people, who would not allow the U.S. government to make such a big mistake."

Withdrawal of U.S. troops from Iraq, meanwhile, would be "the best scenario," Ahmadinejad said. "But I think that it needs a timetable ... the presence of the United States there has not reduced tension and it has not limited terrorism either. In fact, it has increased terrorism."

On hostility between the United States and Iran, Ahmadinejad told King: "The hostility has not been from our end. Up to this day, we have always been interested in having friendly relations."

Iran, he said later, "throughout history ... has demonstrated that it is a nation that is for peace and friendly with others."

And he insisted Iran's nuclear program is for peaceful purposes, despite Western nations' concern to the contrary.

"Their concerns about us are not new," he told King of the West. "They've always been concerned. They were the ones who inspired Saddam [Hussein] to attack Iran and get us involved in an eight-year war. The terrorist groups that killed our president, our prime minister, our officials, are now freely asked to live in the Western countries."

The nuclear issue, he said, has been politicized and is not a legal struggle at all, noting the International Atomic Energy Agency, the U.N.'s nuclear watchdog group, has "not detected any noncompliance or deviation" on the part of Tehran. Watch Ahmadinejad talk about nuclear weapons »

Ahmadinejad spoke extensively of Iran's support for Palestinians. The Iranian leader previously has made statements suggesting that Israel be politically "wiped off the map," though he insists that can be accomplished without violence. He has questioned the existence of the Holocaust, the genocidal Nazi campaign against European Jews, and warned Europeans that they may pay a heavy price for its support of Israel.

He insisted, however, that he and his country wish no harm to Jews.

"We have no problems with Jewish people," he said. "There are many Jews who live in Iran today ... but please pay attention to the fact that the Zionists are not Jews. They have no religion ... they just have -- wear masks of religiosity. How can you possibly be religious and occupy the land of other people?" Watch Ahmadinejad say he has no problems with Jews

On the Holocaust, he said an impartial group should research whether it happened as has been claimed.

"There is a claim that the extent of the calamity was what it was," Ahmadinejad said. "There are people who agree with it. There are people who disagree."

Ahmadinejad has also caused controversy by previously suggesting there were no homosexuals in Iran. Regarding that statement, he told King: "I said it is not the way it is here. In Iran this is considered a very -- obviously, most people dislike it. And we have, actually, a law regarding it and the law is enforced."

However, he said, "we do pay attention that in Iran nobody interferes in the private lives of individuals. We have nothing to do with the private realm of people. This is at the -- non-private, public morality. In their own house, nobody ever interferes."